1. Field of the Invention
The present invention relates to a CRT driving circuit used in a display device using a CRT in a television set or a television set equipped with a video cassette recorder, and more particularly to a CRT driving circuit used to drive the cathode of the CRT.
2. Description of the Related Art
It is well known that with respect to the CRT of a television set or a television set equipped with a video cassette recorder, a monitor screen still illuminates in white spots even after a power switch is turned off. It is said that such a phenomenon, called "remaining spot" or "stray emission", is attributable to a remaining high voltage because electrons are left in the CRT after the power switch is turned off.
This remaining spot impairs the display as a commodity product. In order to obviate such an inconvenience, conventionally, when the power switch is turned off, a so-called "full white" video signal is been applied to a cathode control circuit of the CRT so that the entire screen illuminates in white, and thereafter a power supply circuit is turned off.
However, such a countermeasure does not discharge the high voltage left in the CRT after the power switch is turned off so that it is only a temporary means for making the remaining spot unattractive, not a substantial solution of the inconvenience. In addition, such a countermeasure places the CRT in an excessively loaded state due to the full white image and hence is not preferred to the CRT.